Ontology Loose Coupling Annotation

I've slowly changed my mind since last year about schema.org semantics. The RDFa version of the data model, even if it was still "experimental", has clarified that schema.org notions of "domain" and "range" differ from their RDFS homonyms. I was pleased to see later on the proposal to rename them "domainIncludes" and "rangeIncudes" respectively to avoid further ambiguity, even if this proposal did not address all my questions.

And actually I now look forward to see those properties explicitly published and usable for linked vocabularies, because they offer a new way to link class to properties, alternative to the hard semantic constraints of either rdfs:domain and rdfs:range (often abused because default such alternative), or local constraints using OWL restrictions, more difficult to understand and use. The semantics of domainIncludes and rangeIncludes are indeed more fit to the needs of  loose semantic coupling in the linked data universe. They allow to suggest, indicate without enforcing any logical constraint, the classes that are expected or intended to be found for subjects and objects of a given predicate. They offers good guidelines to linked data publishers and consumers using the predicate. They are a nice workaround avoiding the cumbersome construction of complex domains using owl:unionOf.

Since the publication of those properties in the schema.org namespace does not seem in the top priorities, I decided to make a step forward and define them in a namespace of mine, and to use them in the latest version of the lingvoj.org ontology. This small vocabulary is (so far) called Ontology Loose Coupling Annotation. Not sure this is the most appealing title, maybe Loose Ontology Coupling (LoCo) would fly better.
Anyway ... OLCA, as it stands, defines among other properties olca:domainIncludes and olca:rangeIncludes as owl:AnnotationProperty, so that they can be included in OWL ontologies without interfering with the core semantics. 

I hope it will provide a way for lightly constrained popular vocabularies such as Dublin Core, SKOS and FOAF to play nicely together, through loose coupling declarations such as the one given as example.

dcterms:subject a  rdf:Property

    olca:domainIncludes   foaf:Document;

    olca:rangeIncludes    skos:Concept.

A proposal which seems to address the open range issue for DC terms. One can expect the subject (yes, I know, vocabulary clashes here) of dcterms:subject to be a foaf:Document, and it's OK, and the object to be a skos:Concept, and it's OK, but neither of those are constrained. The same property can link other classes as well, and it's OK. 

OWL ontology for identity on the web

This paper by Valentina Presutti and Aldo Gangemi at SWAP2006 begins with a clear introduction to the issue of resource identity, and the ambiguity of the term resource itself. Then it goes on with a very smart OWL model attempting to articulate the various aspects of this concept. Maybe too smart and conceptual to become really popular, but interestingly enough, it goes against the popular Semantic Web assumption that URI can actually identify "non-addressable things", and is rather in the line of letting the referent entities outside of the identification framework.

The definitions of resource that can be found in literature show ambiguity, making the issue of handling the identification of a web resource very problematic.

Our approach restricts the nature of the web resource to that of a computational object. This choice is motivated by the fact that a resource is something that has to be addressable, and things like cars and people are not addressable for their nature. Hence, it is wrong in principle to use the same mechanism of addressing for entities that have such different sorts.

Ontology Definition Metamodel

Certainly a major step towards semantic interoperability of Topic Maps, RDF, OWL, UML, Common Logic ... Really worth downloading and reading at length.

Situation and Identity

Another paper mined from already quoted page about Semantic Web Software Engineering Task Force. Under the general title comes a very technical subtitle
"A Generalisation of Inverse Functional Properties" which does not speak much to people not aware of arcane details of OWL terminology. "Inverse Functional Properties" should be better named "Identifying Properties", since, according to OWL semantics, two individuals sharing the same value for such a property must be considered as the same one. The abstract says:

This paper examines the notions of situation and identity on the semantic web. The authors define how identity and situation apply to the semantic web, and present methods for using Inverse Functional Properties to utilise these definitions. We present the notion of a Composite Inverse Functional Property in order to exploit the structure of data for identification, and show how these can be used to apply context specific identification.

Context specific identification is really the concept to highlight here.